This invention relates to a device for suppressing a disturbance electric wave for motorcycles which can effectively suppress a radiation disturbance electric wave mainly produced due to a spark discharge of an ignition plug of a spark ignition type gasoline engine mounted on a motorcycle.
A motorcycle provided with an internal combustion engine, particularly a spark ignition type gasoline engine tends to radiate a disturbance electric wave having a radio frequency toward outside. It has recently become important to prevent such disturbance electric wave and regulation of the disturbance electric wave now becomes strengthened.
Many attempts have been made to prevent the disturbance electric wave by using an ignition plug with a resistor incorporated therein, an ignition plug cap with a resistor or an inductor incorporated therein, a shield cord, a shield cap, a distribution resistor high tension cord, etc., but hitherto none has led to fully satisfactory results. In addition, it is difficult to stabilize the disturbance electric wave to a value within upper limit allowable on the basis of Europe Standard (C.I.S.P.R.) or SAE Standard by taking deviation from the standard ignition device, etc. in mass production scale into consideration. In addition, the conventional supressing device is expensive.